The present invention relates to a combined oil ring assembly designed to prevent breakage of the expander and improve its fatigue resistant properties. The combined oil ring assembly or oil control piston ring includes an expander and side rails seated on upper and lower surfaces of the expander, which assembly fits into the groove of a reciprocating piston primarily employed in internal combustion engines. The outer peripheral edges of the side rails contact the inner wall of the cylinder and prevent leakage of oil due to a spring-like property of the expander.